Method for creating stacked plans, apparatus for creating stacked plans, and recording medium

Abstract

The stacking planning method for stacked structures includes the following steps: obtaining shape data; determining the welding passes for each layer obtained by decomposing the three-dimensional shape of the stacked structure into layers; classifying multiple welding passes into cross-region passes and normal region passes; dividing the cross-region passes into lower layer passes and upper layer passes at the cross-section; and determining the welding conditions for the cross-region passes in such a way that the upper layer deposition amount is greater than the lower layer deposition amount, and the sum of the upper layer deposition amount and the lower layer deposition amount is equal to the deposition amount based on the normal region passes, and the contours of adjacent weld beads in the cross section orthogonal to the length direction formed by the weld beads formed by the upper layer passes overlap each other.

Description

Technical Field

[0001] This invention relates to a method, apparatus, and procedure for fabricating a layered design of a layered structure formed by layered weld beads. Background Technology

[0002] In recent years, the demand for 3D printers in production facilities has increased, leading to research and development focused on the practical application of metal-based molding. 3D printers for metal molding use heat sources such as lasers, electron beams, and electric arcs to melt metal powder or filaments, and then layer the molten metal to create laminated models. For example, Patent Document 1 discloses a lamination design method where, in manufacturing laminated models by layering weld beads formed by melting and solidifying filamentous metal material (filler material), the manufacturing process of the laminated model is evaluated through simulation, and the optimal welding passes and welding conditions are adjusted. The molding process is then controlled by the adjusted welding equipment.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-201474

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-111582 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, when forming a laminated structure by stacking multiple weld beads through arc welding, overlapping sections of the weld beads occur depending on the shape of the laminated structure. In the case of forming such intersections, for example, there exists... Figure 18 The method shown involves forming weld bead B2 in a direction orthogonal to weld bead B1 formed along a direction relative to weld bead B1 formed in one direction. In this case, the formation of weld bead B2 is stopped immediately before the previously formed weld bead B1, and then the formation of weld bead B2 begins from a position beyond weld bead B1, thereby shaping the intersection CR. However, in this method, it is easy to encounter problems at the end B of weld bead B2. end With the beginning B bgn Gaps can create internal defects in the stacked form after molding. To suppress these internal defects, welding conditions need to be set with more tuning parameters.

[0009] Furthermore, in the technology of Patent Document 2, in the manufacturing process that includes the contour shaping stage of forming the outline of the layered object and the stage of fusing the filling pattern within the outline, the welding conditions are changed at the intersection where the filling pattern meets the outline, so as not to fuse an amount of metal material as distorting the outline at the intersection. In this case, setting the welding conditions also becomes complicated, and a great deal of labor is required to form the intersection without causing adverse conditions.

[0010] Therefore, the object of the present invention is to provide a method, apparatus and procedure for planning a stacked shape of a stacked object in which the weld beads of the stacked shape are formed at the intersection of the weld beads with uniform stack height in a manner that can prevent the generation of internal defects.

[0011] Solution for solving the problem

[0012] The present invention is composed of the following structure.

[0013] (1) A method for planning the stacking of a stacked object, comprising a stacking molding apparatus for forming weld beads by melting and solidifying filler material through stacking, and shaping the stacked object using shape data representing the three-dimensional shape of the stacked object, wherein,

[0014] The method for planning the stacking of the stacked structure includes the following steps:

[0015] Obtain the shape data;

[0016] Multiple welding passes are determined, and the welding passes form layers obtained by decomposing the three-dimensional shape of the stacked model based on the shape data through the fusion weld passes;

[0017] The multiple welding passes within the same layer of each layer are classified into cross-region passes corresponding to the cross-sections and normal region passes corresponding to the normal portions other than the cross-sections. The cross-sections are formed by the intersection of multiple weld passes formed adjacent to each other.

[0018] The lanes in the intersection area are each divided into lower-level lanes forming the lower layer and upper-level lanes forming the upper layer; and

[0019] The welding conditions for the cross-region passes are determined in such a manner that the upper layer deposition per unit length of the weld bead formed by the upper layer pass is greater than the lower layer deposition per unit length of the weld bead formed by the lower layer pass, and the sum of the upper layer deposition and the lower layer deposition is equal to the deposition per unit length of the weld bead formed by the normal region pass, and the contours of the weld beads adjacent to each other in the cross section orthogonal to the length direction of the weld bead formed by the upper layer pass overlap each other.

[0020] (2) A stacking design fabrication apparatus for fabricating a stacking design, wherein the stacking design utilizes a stacking molding apparatus for forming weld beads by melting and solidifying filler material through stacking, and shapes the stacking design using shape data representing the three-dimensional shape of the stacked design, wherein,

[0021] The stacking planning and fabrication apparatus includes:

[0022] The data acquisition unit acquires the shape data;

[0023] The welding pass determination unit determines multiple welding passes, which are formed by the fusion weld passes to decompose the three-dimensional shape of the stacked model based on the shape data into layers.

[0024] The welding pass classification section classifies the multiple welding passes within the same layer of each layer into cross-region passes corresponding to cross-sections and normal region passes corresponding to normal sections other than the cross-sections. The cross-sections are formed by crossing other multiple weld passes at portions formed adjacent to each other.

[0025] The upper and lower layer dividing section further divides the intersection area into lower layer tracks forming the intersection and upper layer tracks forming the intersection; and

[0026] The welding condition determining unit determines the welding conditions of the cross-region pass in such a manner that the upper layer deposition amount per unit length of the weld bead formed by the upper pass is greater than the lower layer deposition amount per unit length of the weld bead formed by the lower pass, the sum of the upper layer deposition amount and the lower layer deposition amount is equal to the deposition amount per unit length of the weld bead formed by the normal region pass, and the contours of the weld beads that are adjacent to each other in the cross section orthogonal to the length direction of the weld bead formed by the upper pass overlap each other.

[0027] (3) A program that causes a computer to execute a stacking modeling process for a stacked object, the stacking modeling process utilizing a stacking modeling device for melting and solidifying filler material to form weld beads, and using shape data representing the three-dimensional shape of the stacked object to model the stacked object, wherein,

[0028] The program enables the computer to perform the following functions:

[0029] Obtain the shape data;

[0030] Multiple welding passes are determined, and the welding passes form layers obtained by decomposing the three-dimensional shape of the stacked model based on the shape data through the fusion weld passes;

[0031] The multiple welding passes within the same layer of each layer are classified into cross-region passes corresponding to the cross-sections and normal region passes corresponding to the normal portions other than the cross-sections. The cross-sections are formed by the intersection of multiple weld passes formed adjacent to each other.

[0032] The lanes in the intersection area are each divided into lower-level lanes forming the intersection and upper-level lanes forming the intersection; and

[0033] The welding conditions for the cross-region passes are determined in such a manner that the upper layer deposition per unit length of the weld bead formed by the upper layer pass is greater than the lower layer deposition per unit length of the weld bead formed by the lower layer pass, and the sum of the upper layer deposition and the lower layer deposition is equal to the deposition per unit length of the weld bead formed by the normal region pass, and the contours of the weld beads adjacent to each other in the cross section orthogonal to the length direction of the weld bead formed by the upper layer pass overlap each other.

[0034] Invention Effects

[0035] According to the present invention, the intersection of weld beads with uniform stack height is formed in a manner that can prevent the generation of internal defects. Attached Figure Description

[0036] Figure 1 This is a schematic diagram showing the manufacturing apparatus for layered shapes.

[0037] Figure 2 It is a three-dimensional drawing showing the outline shape of a layered structure with intersecting parts.

[0038] Figure 3 This is a functional block diagram of the cascaded planning department.

[0039] Figure 4 The diagrams in (A) and (B) illustrate the process of forming an intersection using weld beads.

[0040] Figure 5 This is a reference diagram showing the situation where the weld beads formed by the cross-region passes in the cross section are formed under the same conditions in the upper and lower layers.

[0041] Figure 6 It is shown Figure 5 The reference diagram shows a cross-section of the weld bead along line VI-VI.

[0042] Figure 7 This is an explanatory diagram showing the situation where the weld beads formed by the cross-region passes in the cross section are formed under different conditions in the upper and lower layers.

[0043] Figure 8 yes Figure 7 The cross-sectional view of the weld bead shown along line VIII-VIII.

[0044] Figure 9 This is an explanatory diagram showing when to change the welding speed at the intersection.

[0045] Figure 10 This is a flowchart illustrating the production process of a layered design.

[0046] Figure 11 This is an explanatory diagram showing the predicted profiles of the upper and lower weld beads in the intersection of Sample 1.

[0047] Figure 12 This is an explanatory diagram showing the predicted profiles of the upper and lower weld beads in the intersection of Sample 2.

[0048] Figure 13 This is an explanatory diagram showing the predicted profiles of the upper and lower weld beads in the intersection of Sample 3.

[0049] Figure 14 This is an explanatory diagram showing the predicted profiles of the upper and lower weld beads in the intersection of Sample 4.

[0050] Figure 15 This is an explanatory diagram showing the predicted profiles of the upper and lower weld beads in the intersection of Sample 5.

[0051] Figure 16 This is an explanatory diagram showing other possible changes in welding speed at the intersection.

[0052] Figure 17 It is a graph showing the relationship between the feed rate (A) of the filler material and the welding speed (B) when restarting after the formation of the lower layer weld bead has stopped.

[0053] Figure 18 This is an explanatory diagram showing the conventional process for forming the intersection of weld beads. Detailed Implementation

[0054] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0055]

[0056] Figure 1 This is a schematic diagram showing the manufacturing apparatus for layered shapes.

[0057] The fabrication apparatus 100 for this structure includes a fabrication unit 11, a controller 13 for comprehensively controlling the fabrication unit 11, and a power supply unit 15. The fabrication unit 11 has a welding robot 19 with a welding torch 17 mounted on its front end shaft and a filler material supply unit 21 for supplying filler material (welding wire) M to the welding torch 17. The fabrication unit 11 uses an electric arc to melt and solidify the filler material M to form weld beads B on a base plate 23, and then sequentially stacks the weld beads B to form a fabricated composite 25. It should be noted that the fabrication apparatus 100 shown here is an example structure, and other structures are also possible.

[0058] The welding robot 19 is a multi-joint robot. The filler material M is supported on a welding torch 17 mounted on the front axis of the robotic arm in a manner that allows for continuous supply. The position and orientation of the welding torch 17 can be arbitrarily set in three dimensions within the range of the robotic arm's degrees of freedom.

[0059] The welding torch 17 has a protective nozzle (not shown) and supplies protective gas from the protective nozzle. The arc welding method used herein can be any of consumable electrode types such as overlay arc welding and carbon dioxide gas arc welding, or non-consumable electrode types such as TIG welding and plasma arc welding, appropriately selected depending on the laminated structure being produced.

[0060] For example, in the case of a consumable electrode type, a conductive tip is disposed inside the protective nozzle, and the filler material M supplied with molten current is held in the conductive tip. While holding the filler material M, the welding torch 17 generates an arc from the tip of the filler material M in a protective gas atmosphere. The filler material M is fed from the filler material supply unit 21 to the welding torch 17 via a delivery mechanism (not shown) mounted on a robotic arm or the like. Furthermore, if the continuously fed filler material M is melted and solidified while the welding torch 17 is moved, a linear weld bead B, which is the molten solidified filler material M, is formed on the base plate 23.

[0061] As filler material M, all commercially available welding wires can be used. For example, welding wires specified such as solid welding wires for MAG welding and MIG welding of mild steel, high-tensile steel and low-temperature steel (JIS Z 3312) or flux-cored welding wires for arc welding of mild steel, high-tensile steel and low-temperature steel (JIS Z 3313) can be used.

[0062] Furthermore, the heat source for melting the filler material M is not limited to the electric arc described above. For example, other heat sources based on methods such as heating with both electric arc and laser, heating with plasma, or heating with electron beam or laser can also be used. When heating with electron beam or laser, the amount of heat can be controlled more precisely, and the state of the weld bead can be maintained more appropriately, which helps to further improve the quality of the laminated structure.

[0063] The controller 13 includes a stacked planning unit 27, a storage unit 29, and a control unit 31 connected to them. The controller 13 is composed of a computer device including a CPU, memory, and storage.

[0064] The stacking planning unit 27 generates a shape model that becomes the target shape based on the three-dimensional shape data (CAD data, etc.) of the stacked model 25 to be produced, and decomposes the obtained shape model into multiple weld bead layers corresponding to the height of the weld bead B. Then, for each layer of the decomposed shape model, a stacking plan is created that determines the weld bead formation pass (the track of the welding torch 17 used to form the weld bead B) and the welding conditions for forming the weld bead B (including heating conditions such as welding current and welding voltage, or welding conditions, etc., used to obtain the weld bead width, weld bead stacking height, etc.).

[0065] That is, the shape model layer, which is the target shape, is divided into multiple weld bead models with shapes corresponding to the weld beads, and the weld bead formation sequence and welding conditions in each divided layer are determined. The created layer stack plan is stored in the storage unit 29 as a driver program for each part of the layer stack modeling device 11.

[0066] According to the manufacturing apparatus 100 for the stacked model with the above-described structure, the control unit 31 executes the drive program stored in the storage unit 29 to drive the welding robot 19 and the power supply unit 15. That is, the controller 13 drives the welding robot 19 according to the process set in the drive program, causing the welding torch 17 to move along the weld bead formation sequence, and using an electric arc to heat the filler material M at the tip of the welding torch, thereby depositing the molten filler material M onto the base plate 23. As a result, a stacked model 25 with multiple linear weld beads B formed on the base plate 23 is obtained.

[0067] It should be noted that the necessary information can also be input to other computer devices different from controller 13, and the cascading plan and driver can be generated on the other computer device. In this case, the cascading plan unit 27 is composed of a computer device equipped with a CPU, memory and storage, and the generated cascading plan information and driver are input to the storage unit 29 of controller 13 via a suitable communication mechanism such as LAN.

[0068] Figure 2This is a perspective view showing the outline shape of the layered structure 25 with intersecting parts.

[0069] As an example, the stacked structure 25 is formed by stacking multiple rows (3 rows) of adjacent weld beads B1 formed along one direction (X direction) and multiple rows (3 rows) of adjacent weld beads B2 formed along a direction orthogonal to one direction (Y direction) in the height direction (Z direction) in multiple layers (3 layers). The portion where these weld beads B1 and B2 intersect (the portion surrounded by the dashed line shown on the uppermost layer of the weld beads) is designated as the intersection CR, and the portion other than the intersection CR is designated as the normal portion RE. Actual stacked structures are mostly more complex than the above-described shapes, but the simple shape of the intersection CR is used here for explanation.

[0070] When creating a stacked design 25 with the aforementioned cross section CR, the welding conditions for the weld bead are set such that the stacking height of the cross section CR after forming weld beads B1 and B2 is consistent with the stacking height of the normal section RE, thereby suppressing the generation of internal defects.

[0071] Figure 3 This is the functional block diagram of the cascaded planning section 27.

[0072] The layer planning unit 27 includes a data acquisition unit 33, a welding pass determination unit 35, a welding pass classification unit 37, an upper and lower layer division unit 39, and a welding condition determination unit 41.

[0073] The data acquisition unit 33 acquires the shape data of the stacked model 25 that becomes the modeling object, and the welding pass determination unit 35 determines the welding pass order based on the shape data. Figure 1 The welding torch 17's movement trajectory is shown. The welding pass classification unit 37 and the upper / lower layer segmentation unit 39 extract and adjust the welding pass of the intersection CR. The welding condition determination unit 41 determines the welding conditions for the welding pass of the intersection CR. The resulting stack-up plan is output as data containing stack-up plan information or as the aforementioned driver program. Details of the processing in each part will be described later.

[0074] <Cascaded Project Creation Method>

[0075] The following section explains the basic stacking scheme based on this stacking scheme creation method.

[0076] Figure 4 The diagrams in (A) and (B) illustrate the process of forming an intersection using weld beads.

[0077] Here, for those with Figure 2 The layering plan of the layered shape 25 of the cross section CR shown will be explained.

[0078] Figure 4 (A) shows the welding passes (torch movement trajectories) L1, L2, and L3 forming three columns of weld beads along one direction. Additionally, Figure 4 (B) shows welding passes L4, L5, and L6, which form three columns of weld beads along a direction orthogonal to the aforementioned welding passes L1, L2, and L3. It should be noted that the number of columns in the welding passes is arbitrary; three columns are shown here as an example.

[0079] Each welding pass L1 to L6 can be classified into the intersection CR where weld passes intersect each other and the normal section RE outside the intersection CR. The welding passes included in the area of ​​the normal section RE are designated as normal section passes L. R1 L R2 The welding passes included in the area of ​​the intersection CR are set as the intersection area pass number L. C .

[0080] for Figure 4 The welding passes L1, L2, and L3 shown in (A) make the pass number L in the intersection area... C Welding speed V a2 Compared to the normal area L up to the intersection CR R1 and the usual area L after crossing the intersection CR R2 Welding speed V a1 Fast (V) a1 <V a2 ).

[0081] In addition, for Figure 4 Similarly, the welding passes L4, L5, and L6 shown in (B) also have the same crossover pass number L. C Welding speed V b2 Compared to the normal area L up to the intersection CR R1 and the usual area L after crossing the intersection CR R2 Welding speed V b1 Fast (V) b1 <V b2 ).

[0082] When the welding speed is increased, the amount of weld deposited per unit length decreases, thus reducing the height of the weld bead. This can be used to reduce the weld bead height in the intersection area of ​​welding passes L1, L2, and L3. C and the intersection area of ​​welding passes L4, L5, and L6, pass L C The sum of the welding amount and the number of passes in the usual area L R1 L R2 The welding speed is adjusted to ensure that the deposition amount is equal. In this way, the welding speed in the intersection area of ​​welding passes L1, L2, and L3 is adjusted. CIntersection area with welding passes L4, L5, and L6, pass L C The total height of the weld beads formed by overlapping the upper and lower sections is equal to the height of the weld beads formed by the normal section RE.

[0083] Figure 5 This is a reference diagram showing the situation where the weld beads formed by the cross region passes in the cross section CR are formed under the same conditions in the upper and lower layers.

[0084] like Figure 5 As shown, in the intersection CR, Figure 4 (A) shows the intersection area of ​​the first weld passes L1, L2, and L3, pass L. C These become the next layer passes, forming weld beads B1, B2, and B3. Additionally, Figure 4 (B) shows the intersection area of ​​welding passes L4, L5, and L6, where pass L is formed later. C These become the upper layers, forming weld beads B4, B5, and B6.

[0085] However, as Figure 5 As shown, when the sum of the deposition amounts of the lower and upper passes is equal to the deposition amount of the normal zone passes, and the welding speed of the lower pass in the intersection CR is equal to the welding speed of the upper pass, the deposition amounts from the lower and upper passes each become half of those from the normal zone passes. In this case, the weld width W of the weld bead formed by the lower pass... c1 And the weld width W of the weld bead formed by the upper pass. c2 Compared to the weld width Wr of a typical zone pass, the weld bead width is smaller, resulting in a gap S in the area of ​​the intersection CR where no weld bead has been formed.

[0086] Figure 6 It is shown Figure 5 The reference diagram shows a cross-section of the weld bead along line VI-VI.

[0087] like Figure 6 As shown, weld beads B4, B5, and B6, formed by the upper pass, are formed on top of weld bead B1, which is formed by the lower pass. The weld width W of weld beads B4, B5, and B6 is... c2 All are narrower than the center spacing PT of the weld bead, and the angle θ between the valleys formed by the undulations of the weld bead becomes smaller. Thus, the undulations of the weld beads B4, B5, and B6 formed by the upper layers are formed by the steep slope of the lower weld bead B1, and the unevenness of the weld bead surface becomes deeper.

[0088] Figure 7This is an explanatory diagram showing the situation where the weld beads formed by the cross region passes in the cross section CR are formed under different conditions in the upper and lower layers.

[0089] like Figure 7 As shown, the sum of the deposition amounts of the lower and upper passes is made equal to the deposition amount of the passes in the normal area, and the welding speed of the upper passes in the intersection CR is made slower than that of the lower passes. Thus, in the intersection CR, the weld width W of the first deposited weld beads B1, B2, and B3 is... c1 Compared to the aforementioned Figure 5 The weld width W shown c1 Narrow. Additionally, the weld width W of the subsequently formed weld beads B4, B5, and B6... c2 Compared to the aforementioned Figure 5 The weld width W shown c2 Wide, with adjacent weld beads overlapping each other.

[0090] Figure 8 yes Figure 7 The cross-sectional view of the weld bead shown along line VIII-VIII.

[0091] like Figure 8 As shown, the weld bead B1 formed by the lower pass has a lower weld bead height due to the faster welding speed, but the weld bead width W of the weld beads B4, B5, and B6 formed by the upper pass is higher. c2 The spacing PT between the weld beads is wider than the center of the weld bead, resulting in a smoother weld bead undulation. Consequently, adjacent weld beads overlap on weld bead B1, and the angle θ of the resulting valley is... Figure 6 The situation shown is larger. Thus, the undulations of weld beads B4, B5, and B6 formed by the upper passes are formed by the gentle slope of the lower weld bead B1, resulting in a shallower surface unevenness. In other words, weld beads formed by the upper passes are formed seamlessly over the weld beads formed by the lower passes.

[0092] Next, the welding conditions will be explained in more detail.

[0093] The amount of weld deposit S in the above-mentioned weld bead is expressed by equation (1).

[0094] [Mathematical Formula 1]

[0095]

[0096] S: Deposition amount (deposition volume per unit length [1 mm])

[0097] V wire : Feed rate of filler material [m / min]

[0098] Vweld Welding speed [cm / min]

[0099] r: Radius of the filling material [mm]

[0100] μ: Melt adhesion rate (usually 1–0.98)

[0101] The welding conditions for the normal part can be set, for example, as follows.

[0102] V wire 5.2 [m / min]

[0103] V weld (V) a1 V b1 ): 74 [cm / min]

[0104] S: 7.8 [mm] 3 ]

[0105] Preferably, in the cross section CR, the weld beads formed by the lower passes should produce as little weld deposit as possible. Therefore, the welding speed V, which is the maximum moving speed of the robot supporting the welding torch, should be used. weld When the speed is set to 300 [cm / min], the deposition amount (lower layer deposition amount) S1 of the weld bead formed by the lower layer becomes 1.9 mm. 3 Furthermore, in order to make the deposition amount of the cross section CR equal to that of the normal section RE, the deposition amount of the weld bead formed by the upper pass (upper layer deposition amount) S2 is calculated according to equation (2), which is 7.8 - 1.9 = 5.9 mm. 3 .

[0106] S2 = S - S1 … (2)

[0107] If we calculate the welding conditions for the upper pass under this condition, then when the feed rate of the filler material is kept at 5.2 [m / min], the welding speed becomes 97 [cm / min].

[0108] To ensure consistent surface properties of the weld bead, the width of the weld bead formed by the previous pass needs to be controlled to remain as constant as possible. Therefore, a smaller weld bead ratio S1 / (S1+S2) is preferable. When setting a threshold (upper limit) for the ratio S1 / (S1+S2), for example, the value at which defects begin to appear between adjacent weld beads can be set as the threshold.

[0109] Here, we consider the case where the intersection CR of the weld bead is formed by three intersecting rows of weld beads. For example... Figure 5 As shown, when the upper layer deposition amount S2 of weld beads B4, B5, and B6 formed by the upper layer passes is small, the welding speed V when entering the intersection section CR from the normal section RE is...weld The variation is large (in the welding speed V of the normal part) weld When the welding speed V at the intersection is 74 cm / min, weld The weld width of the intersection CR is 150 cm / min, therefore the weld width of the intersection CR is smaller than that of the normal section RE.

[0110] Furthermore, since the distance between adjacent weld beads remains constant, the undulations between weld beads become larger, and the angle θ between the valleys becomes smaller. When the angle θ between the valleys becomes smaller, narrow and deep slits are created. When weld beads are continuously stacked on top of these slits, the slits do not completely melt and remain as internal defects.

[0111] On the other hand, such as Figure 7 As shown, by reducing the difference between the upper layer deposition amount S2 of weld beads B4, B5, and B6 formed by the upper passes and the deposition amount of the normal portion RE, the variation in weld bead width of weld beads B4, B5, and B6 formed by the upper passes is small, resulting in weld beads with a shape approximately the same as the normal portion RE. Therefore, thin and deep narrow portions are not generated, and internal defects are less likely to occur. It should be noted that, in this structure, the angle θ between the valleys is set to an angle exceeding 40°, preferably exceeding 50°, and more preferably exceeding 60°. The desired angle θ varies depending on various conditions such as the material and the shape of the object.

[0112] As mentioned above, if the welding speed and other limited tuning parameters are set based on the deposition amount, it is possible to create a shape that prevents the generation of internal defects and to easily set the stacking conditions of the intersections without any adverse conditions.

[0113] Figure 9 This is an explanatory diagram showing when to change the welding speed at the intersection.

[0114] When the intersection CR of the weld bead is formed by a welding pass La from one side and a welding pass Lb from the other side, the intersection point Pc of welding passes La and Lb is determined based on the coordinate information of the welding passes. Furthermore, the weld bead width W formed by welding pass La is determined based on the aforementioned information such as the weld deposition amount.

[0115] Here, the intersection CR is defined as a range centered at the intersection point Pc, extending forward and backward along the welding directions of welding passes La and Lb, with a weld width of W / 2 on each side. Within this intersection CR, the welding speed is changed from the normal zone pass welding speed V1 to V2 in the aforementioned intersection zone pass Lc. That is, the timing for starting the welding speed change in welding pass Lb is set at the moment when the weld reaches the intersection CR from the normal zone RE, i.e., at position P, which is a distance of W / 2 backwards from the intersection point Pc. BFAdditionally, the timing for returning the welding speed to the normal range of pass rates (V1) is set at position P, which is a distance W / 2 forward from the intersection point Pc. AF Similarly, for welding pass La, the position from the intersection point Pc back a distance of W / 2 along welding pass La to the position from the intersection point Pc forward a distance of W / 2 along welding pass La is set as the welding speed V2.

[0116] In this way, by setting the location for changing the welding speed to a position half the distance from the intersection point Pc away from the weld width W, it is possible to eliminate local over- or under-deposition of the weld near the speed change point. Consequently, the weld bead can be formed into a smooth shape without local unevenness in the layered structure.

[0117] <The Production Process of Layered Project>

[0118] Next, the process of creating a stacking plan that sets the number of weld passes and welding conditions for the stacked model is explained in detail.

[0119] Figure 10 This is a flowchart illustrating the creation process of a stack-up plan. The creation of the stack-up plan here is handled by... Figure 3 The layered planning section 27 shown is performed.

[0120] First, the data acquisition unit 33 reads the three-dimensional shape data (St.1) representing the target shape of the layered object to be created.

[0121] The welding pass determination unit 35 generates a three-dimensional shape model based on the acquired shape data, and divides the obtained shape model into layers obtained by forming a single weld bead. That is, the shape model is divided into multiple layers according to the height of the weld bead B. Then, for each of the obtained multiple layers, a welding torch 17 (for forming the weld bead) is determined. Figure 1 The welding pass (St.2) of the track.

[0122] Next, the welding pass classification unit 37 classifies the multiple welding passes within the same layer of each segmented layer into cross-region passes and normal region passes (St.3) corresponding to the normal parts other than the cross-regions.

[0123] The welding condition determination unit 41 sets welding conditions (including heating conditions such as welding current and welding voltage, and filler material feed rate, etc.) for welding passes classified as normal zone passes to form weld beads (St.4).

[0124] On the other hand, for welding passes classified as cross-region passes, after dividing them into lower passes constituting the cross-region and upper passes constituting the upper layer using the upper and lower layer division section 39, welding conditions are set using the welding condition determination section 41. Specifically, firstly, the presence or absence of defects is determined by simulation or experimental measurement of the ratio of the lower layer deposition amount S1 per unit length of the weld bead formed by the lower pass to the upper layer deposition amount S2 per unit length of the weld bead formed by the upper pass, specifically the ratio of deposition amount S1 / (S1+S2), and a threshold R (St.5) is determined as the critical value for not generating defects.

[0125] When determining this threshold R, a specific indicator can be the angle θ of the valley formed between adjacent weld beads in a cross-section orthogonal to the length direction due to the undulations of multiple weld beads formed by the upper passes. Such a shape can be experimentally determined through actual modeling, but the angle θ of the valley can also be predicted with sufficient accuracy by setting the cross-sectional shape of the weld bead to a simple shape such as a trapezoid and analytically determining it.

[0126] Alternatively, as mentioned above, the critical value of the valley angle θ can be set to 40° as an example. The ratio S1 / (S1+S2) of the critical melt amount when the angle θ is above 40° can be calculated, and this critical ratio can be set as the threshold R. It should be noted that the threshold R can also be determined using information such as the defect table generated before the layering model is built up.

[0127] Furthermore, to ensure that the sum of the lower layer deposition amount S1 and the upper layer deposition amount S2 is equal to the deposition amount per unit length of the weld bead formed by the normal zone passes, and that the deposition amount ratio S1 / (S1+S2) is below a predetermined threshold R, the lower layer deposition amount S1 and the upper layer deposition amount S2 are temporarily set (St.6). Under welding conditions that are below this threshold R, such as Figure 8 As shown, in the cross section orthogonal to the length direction of the weld bead formed by the upper layer passes, the outlines of adjacent weld beads overlap each other.

[0128] Next, based on the temporarily set ratio of deposited amount, the welding speed V2 of the deposited weld bead formed by the next layer pass is calculated (refer to...). Figure 4 (A) shows Va2 and Vb2 (St.7). Determine whether the calculated welding speed V2 is the highest speed V that can be achieved by the welding robot. max below (V2≤V max (St. 8).

[0129] When the welding speed V2 exceeds the maximum speed V maxIn this case, increase the lower layer deposition amount S1 (St.9), and restart from step St.7. At the highest speed V... max In the following cases, determine whether the ratio of deposition amount S1 / (S1+S2) is below the threshold R (St.10). If it exceeds the threshold R, adjust the feed rate V of the filler material. wire Reduce (St.11), and repeat from step St.7. If it is below the threshold R, determine the temporary lower layer deposition amount S1 and upper layer deposition amount S2, and determine the welding conditions based on S1 and S2 (St.12).

[0130] <Verification of the ratio of weld deposition>

[0131] Here, the quality of the designs of samples formed by various ratios S1 / (S1+S2) was judged.

[0132] Figures 11-15 This is an explanatory diagram showing the predicted profiles of the upper and lower weld beads in the intersection of samples 1 to 5. Table 1 summarizes the ratio S1 / (S1+S2), welding speed, and the results of the quality assessment for each sample 1 to 5.

[0133] [Table 1]

[0134]

[0135] Figures 11-13 The upper weld beads of samples 1-3 shown have overlapping portions formed by adjacent weld beads overlapping each other on the lower weld beads. On the other hand, Figure 14 , Figure 15 The upper weld beads of samples 4 and 5 shown do not overlap with the lower weld beads.

[0136] Based on the above results, it can be determined that no welding defects occurred when the ratio S1 / (S1+S2) was below 0.4 in samples 1-3. Furthermore, it can be determined that when the ratio S1 / (S1+S2) exceeded 0.4 in samples 4 and 5, gaps formed between the upper weld beads, potentially leading to internal defects. Thus, when the material, shape, and other conditions are determined, the critical value of the ratio at which internal defects might occur can be calculated.

[0137] <Other examples of welding speed settings>

[0138] Figure 16 This is an explanatory diagram showing other possible changes in welding speed at the intersection.

[0139] A weld bead is formed by a welding pass La from one side and a welding pass Lb from the other side that intersects it. At this point, P is defined as the position where half the weld bead width W of the weld bead formed by welding pass La is traced back along welding pass La from the intersection point Pc of welding pass La and welding pass Lb. BF Place this position P BF The welding speed is set to the midpoint of the range from the start to the end of the welding speed change.

[0140] That is, with position P BF Centered on, so that Figure 16 The areas of triangles A1 and A2, represented by the shaded lines indicating width d, are equal, allowing the welding speed to gradually increase from V1 (normal zone pass) to V2 (intersection zone pass). The width d is set within the range of 0 < d ≤ W / 2. By varying the welding speed within ±d, centered at a point half the weld width W along the welding pass Lb from the intersection point Pc, the resulting weld bead width becomes more uniform, resulting in a consistently high weld width. Similarly, when returning the welding speed from V2 to V1, the speed can be adjusted within ±d, centered at a point half the weld width W along the welding pass Lb.

[0141] <The intersection is formed using only the upper layer of weld beads>

[0142] In the above-described layered molding process, the lower layer weld beads are overlapped with the upper layer weld beads to form an intersection. However, it is also possible to stop the formation of the lower layer weld beads while maintaining the continuity of the welding passes, and only use the upper layer weld beads to form the intersection.

[0143] For example, for Figure 4 During the intersecting zone Lc of welding passes L1, L2, and L3 shown in (A), the feed rate of the filler material in the lower pass is set to 0 to stop the supply of filler material, thereby stopping the formation of the lower weld bead. Furthermore, at the position where weld bead formation has stopped, welding conditions are set such that the weld bead formed by the upper pass has the same weld bead deposition amount as the weld bead in the normal zone pass.

[0144] In this case, it is preferable to temporarily stop the formation of the weld bead in the next pass, and then control the feed rate of the filler material to be synchronized with the change in the welding speed when restarting.

[0145] Figure 17 It is a graph showing the relationship between the feed rate (A) of the filler material and the welding speed (B) when restarting after the formation of the lower layer weld bead has stopped.

[0146] like Figure 17 As shown in (A), the feed rate of the filling material is 0 upon restart, but gradually increases to the set feed rate during the period up to time ta. With this gradual increase in feed rate, as... Figure 17 As shown in (B), the welding speed is gradually reduced. That is, the welding speed increases in the next pass upon restart, but gradually decreases to the welding speed set for the normal zone pass during the period up to time ta.

[0147] It should be noted that it is also possible not to completely stop the formation of the weld bead using the lower passes, but to keep the welding torch in a state of producing a minimum arc and thus keep the weld bead deposition as small as possible. In this case, a state that is substantially similar to the situation where the formation of the lower passes is completely stopped can be obtained.

[0148] This invention is not limited to the above-described embodiments. Combining the various structures of the embodiments with each other, as well as making changes and applications based on the description and well-known techniques by those skilled in the art, are also intended by this invention and are included within the scope of the claims.

[0149] As stated above, the following matters are disclosed in this specification.

[0150] (1) A method for planning the stacking of a stacked object, comprising a stacking molding apparatus for forming weld beads by melting and solidifying filler material through stacking, and shaping the stacked object using shape data representing the three-dimensional shape of the stacked object, wherein,

[0151] The method for planning the stacking of the stacked structure includes the following steps:

[0152] Obtain the shape data;

[0153] Multiple welding passes are determined, and the welding passes form layers obtained by decomposing the three-dimensional shape of the stacked model based on the shape data through the fusion weld passes;

[0154] The multiple welding passes within the same layer of each layer are classified into cross-region passes corresponding to the cross-sections and normal region passes corresponding to the normal portions other than the cross-sections. The cross-sections are formed by the intersection of multiple weld passes formed adjacent to each other.

[0155] The lanes in the intersection area are each divided into lower-level lanes forming the intersection and upper-level lanes forming the intersection; and

[0156] The welding conditions for the cross-region passes are determined in such a manner that the upper layer deposition per unit length of the weld bead formed by the upper layer pass is greater than the lower layer deposition per unit length of the weld bead formed by the lower layer pass, and the sum of the upper layer deposition and the lower layer deposition is equal to the deposition per unit length of the weld bead formed by the normal region pass, and the contours of the weld beads adjacent to each other in the cross section orthogonal to the length direction of the weld bead formed by the upper layer pass overlap each other.

[0157] According to the stacking plan method of this stacked model, the cross area passes are divided into upper passes and lower passes and their respective welding conditions are set, so that it is easy to make a stacking plan that prevents the generation of internal defects in the cross section of the weld bead intersection and can form weld beads with uniform stacking height.

[0158] (2) The layering plan method for the layered structure described in (1), wherein,

[0159] In the process of determining the welding conditions for the cross-region passes, the deposition amount is changed by making the welding speed of the upper pass in the cross-region passes slower than that of the lower pass.

[0160] According to the stacking plan method of this stacked structure, the amount of weld deposit can be appropriately adjusted by changing the welding speed, which can be easily adjusted.

[0161] (3) The stacking plan method for the stacked structure described in (2), wherein,

[0162] During the process of forming the weld bead from the normal portion to the intersection portion, the change of welding speed begins from a position that is half the length of the weld bead width orthogonal to the weld bead length direction of the normal portion, tracing back from the center position of the intersection portion.

[0163] According to the stacking plan method of this laminated structure, local over- or under-deposition of the weld bead in areas with varying weld bead amounts can be eliminated, resulting in a smooth weld bead shape. Therefore, it is possible to prevent local unevenness in the laminated structure.

[0164] (4) The stacking plan method for the stacked structure described in (2), wherein,

[0165] During the process of forming the weld bead from the normal portion to the intersection portion, the welding speed is changed by setting a position at the center of the range from the start to the end of the change of the welding speed, which is half the length of the weld bead orthogonal to the weld bead length direction of the normal portion, back from the center position of the intersection portion.

[0166] According to the stacking plan method of this stacked structure, by continuously changing the welding speed, it is possible to more reliably eliminate excess or insufficient deposition and make the weld bead shape smooth.

[0167] (5) A method for planning the stacking of a stacked structure according to any one of (2) to (4), wherein,

[0168] In addition to the welding speed, the feed rate of the filler material is also changed.

[0169] According to the stacking plan method of this stacked model, in addition to the welding speed, the feed speed of the filler material is also changed, thereby expanding the adjustment range.

[0170] (6) The stacking plan method for the stacked structure described in (1), wherein,

[0171] In the process of determining the welding conditions of the cross-region pass, the formation of the weld bead based on the lower pass in the cross-region pass is stopped, and the weld bead is formed only through the upper pass.

[0172] According to the layering plan method of this layered model, while maintaining the continuous welding track of the lower layer pass of the normal part and the intersection part, the intersection part is formed only through the upper layer pass, so that gaps are not easily generated at the boundary between the normal part and the intersection part, and the generation of internal defects can be suppressed.

[0173] (7) The stacking plan method for the stacked structure described in (6), wherein,

[0174] When restarting after the formation of the weld bead has stopped, the feed rate of the filler material is set to be lower than the feed rate before the formation of the weld bead stopped, and then gradually increased from the lower rate to the feed rate before the formation stopped.

[0175] According to the stacking plan method of this stacked structure, even when the weld formation is restarted after a temporary halt, a smooth and continuous weld bead can be formed.

[0176] (8) The stacking plan method for the stacked structure described in (7), wherein,

[0177] During the period from the restart until the feed rate of the filler material reaches the feed rate before the formation of the weld bead stops, the welding speed is gradually reduced from the welding speed of the cross region passes to the welding speed of the normal region passes.

[0178] According to the stacking plan method of this stacked structure, the feed rate of the filler material is adjusted in combination with the welding speed, so the control of the deposition amount becomes more accurate and a smoother deposition weld can be formed.

[0179] (9) A method for planning the stacking of a stacked structure according to any one of (1) to (8), wherein,

[0180] In the process of determining the welding conditions for the cross zone passes, when the lower layer deposition amount is set to S1 and the upper layer deposition amount is set to S2, the ratio S1 / (S1+S2) of the lower layer deposition amount S1 to the total deposition amount (S1+S2) is set according to the interval between the welds of the plurality of weld passes in the cross zone.

[0181] According to the layering plan method of this layered structure, the lower layer welding amount and the upper layer welding amount are managed at a specified ratio, thereby enabling a more accurate determination of the welding amount at the intersection.

[0182] (10) A stacking design fabrication apparatus for fabricating a stacking design, wherein the stacking design utilizes a stacking molding apparatus for forming weld beads by melting and solidifying filler material through stacking, and shapes the stacking design using shape data representing the three-dimensional shape of the stacked design, wherein,

[0183] The stacking planning and fabrication apparatus includes:

[0184] The data acquisition unit acquires the shape data;

[0185] The welding pass determination unit determines multiple welding passes, which are formed by the fusion weld passes to decompose the three-dimensional shape of the stacked model based on the shape data into layers.

[0186] The welding pass classification section classifies the multiple welding passes within the same layer of each layer into cross-region passes corresponding to cross-sections and normal region passes corresponding to normal sections other than the cross-sections. The cross-sections are formed by crossing other multiple weld passes at portions formed adjacent to each other.

[0187] The upper and lower layer dividing section further divides the intersection area into lower layer tracks forming the intersection and upper layer tracks forming the intersection; and

[0188] The welding condition determining unit determines the welding conditions of the cross-region pass in such a manner that the upper layer deposition amount per unit length of the weld bead formed by the upper pass is greater than the lower layer deposition amount per unit length of the weld bead formed by the lower pass, the sum of the upper layer deposition amount and the lower layer deposition amount is equal to the deposition amount per unit length of the weld bead formed by the normal region pass, and the contours of the weld beads that are adjacent to each other in the cross section orthogonal to the length direction of the weld bead formed by the upper pass overlap each other.

[0189] According to the stacking plan device of this stacked model, the cross area passes are divided into upper passes and lower passes and their respective welding conditions are set, so that it is easy to make a stacking plan that prevents the generation of internal defects in the cross section of the weld bead intersection and can form weld beads with uniform stacking height.

[0190] (11) A program that causes a computer to execute a stacking modeling process for a stacked object, the stacking modeling process utilizing a stacking modeling device for forming weld beads by melting and solidifying filler material, and using shape data representing the three-dimensional shape of the stacked object to model the stacked object, wherein,

[0191] The program enables the computer to perform the following functions:

[0192] Obtain the shape data;

[0193] Multiple welding passes are determined, and the welding passes form layers obtained by decomposing the three-dimensional shape of the stacked model based on the shape data through the fusion weld passes;

[0194] The multiple welding passes within the same layer of each layer are classified into cross-region passes corresponding to the cross-sections and normal region passes corresponding to the normal portions other than the cross-sections. The cross-sections are formed by the intersection of multiple weld passes formed adjacent to each other.

[0195] The lanes in the intersection area are each divided into lower-level lanes forming the intersection and upper-level lanes forming the intersection; and

[0196] The welding conditions for the cross-region passes are determined in such a manner that the upper layer deposition per unit length of the weld bead formed by the upper layer pass is greater than the lower layer deposition per unit length of the weld bead formed by the lower layer pass, and the sum of the upper layer deposition and the lower layer deposition is equal to the deposition per unit length of the weld bead formed by the normal region pass, and the contours of the weld beads adjacent to each other in the cross section orthogonal to the length direction of the weld bead formed by the upper layer pass overlap each other.

[0197] According to this procedure, it is possible to easily create a stacking plan that prevents the generation of internal defects in the intersection of weld beads and enables the formation of weld beads with a uniform stacking height.

[0198] It should be noted that this application is based on the Japanese patent application (Japanese Patent Application No. 2021-25576) filed on February 19, 2021, the contents of which are referenced in this application.

[0199] Explanation of reference numerals in the attached figures

[0200] 11 Layered Modeling Installation

[0201] 13 Controllers

[0202] 15 Power supply unit

[0203] 17 Welding torch

[0204] 19 Welding Robots

[0205] 21. Filler Material Supply Department

[0206] 23 Base Plate

[0207] 25 layered structures

[0208] 27 Layered Planning Department

[0209] 29 Storage Department

[0210] 31 Control Department

[0211] 33 Data Acquisition Department

[0212] 35 Welding Pass Determination Department

[0213] 37 Welding Pass Classification Department

[0214] 39. Upper and lower layer division

[0215] 41 Welding Condition Determination Department

[0216] 100 Manufacturing Equipment

[0217] B, B1, B2, B3, B4, B5, B6 weld beads

[0218] CR cross section

[0219] Welding passes L1, L2, L3, L4, L5, L6, La, Lb

[0220] L c Intersection area lanes

[0221] L R1 L R2 Typical regional routes

[0222] M. Filler material (welding wire)

[0223] Pc intersection

[0224] RE (Regular Section)

[0225] S welding amount

[0226] S1 Lower layer deposition amount (deposition amount)

[0227] S2 Upper Layer Deposition Amount (Deposition Amount)

[0228] V1, V2, V a1 V a2 V b1 V b2 Welding speed

[0229] θ is the angle.

Claims

1. A layering planning method of a layered object, using a layered object manufacturing apparatus that forms a deposited bead by melting and solidifying a filler material by layering, the layered object being manufactured using shape data that indicates a three-dimensional shape of the layered object, wherein the layering planning method of the layered object comprises the following steps: obtaining the shape data; determining a plurality of welding passes that form each layer obtained by layer-decomposing the three-dimensional shape of the layered object based on the shape data by the deposited bead; classifying a plurality of the welding passes within the same layer of the each layer into a cross region pass corresponding to a cross portion and a normal region pass corresponding to a normal portion other than the cross portion, the cross portion being formed by a portion of a plurality of the deposited beads formed adjacently intersecting other plurality of the deposited beads; dividing the cross region pass into a lower layer pass that forms a lower layer of the cross portion and an upper layer pass that forms an upper layer of the cross portion; and determining welding conditions of the cross region pass in such a manner that a upper layer deposition amount per unit length of the deposited bead formed by the upper layer pass is larger than a lower layer deposition amount per unit length of the deposited bead formed by the lower layer pass, a sum of the upper layer deposition amount and the lower layer deposition amount is equal to a deposition amount per unit length of the deposited bead formed by the normal region pass, and outlines of the deposited beads formed by the upper layer pass overlap each other in a cross section of the deposited bead formed by the upper layer pass orthogonal to a length direction.

2. The layering planning method of a layered object according to claim 1, wherein in a process of forming the deposited bead from the normal portion to the cross portion, the change in the welding speed is started from a position that is a length of a half of a bead width of the normal portion orthogonal to a bead length direction from a center position of the cross portion.

3. The layering planning method of a layered object according to claim 1, wherein in a process of forming the deposited bead from the normal portion to the cross portion, the welding speed is changed so that a position that is a length of a half of a bead width of the normal portion orthogonal to a bead length direction from a center position of the cross portion is set as a central position of a range from a start to an end of the change in the welding speed.

4. The layering planning method of a layered object according to any one of claims 1 to 3, wherein a feed speed of the filler material is changed in addition to the welding speed.

5. The layering planning method of a layered object according to any one of claims 1 to 3, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In the process of deciding the welding conditions of the cross region passes, when the lower layer deposition amount is set to S1 and the upper layer deposition amount is set to S2, the ratio S1 / (S1+S2) of the lower layer deposition amount S1 to the total deposition amount (S1+S2) is set according to the interval of the welding passes of the plurality of deposition welds in the intersection portion.

6. The layering plan method of a layering object according to claim 4, wherein In the process of deciding the welding conditions of the cross region passes, when the lower layer deposition amount is set to S1 and the upper layer deposition amount is set to S2, the ratio S1 / (S1+S2) of the lower layer deposition amount S1 to the total deposition amount (S1+S2) is set according to the interval of the welding passes of the plurality of deposition welds in the intersection portion.

7. A layering plan production device that produces a layering plan for a layering object production device that produces a deposition weld by melting and solidifying a filler material in layers, the layering object production device using shape data representing a three-dimensional shape of the layering object to produce the layering object, wherein the layering plan production device comprises: a data acquisition section that acquires the shape data; a welding pass decision section that decides a plurality of welding passes that form each layer obtained by layering the three-dimensional shape of the layering object based on the shape data by the deposition weld; a welding pass classification section that classifies a plurality of the welding passes within the same layer of the each layer into a cross region pass corresponding to an intersection portion and a normal region pass corresponding to a normal portion other than the intersection portion, the intersection portion being formed by a portion where a plurality of the deposition welds are formed adjacent to each other intersecting other plurality of the deposition welds; a lower and upper layer division section that divides each of the cross region passes into a lower layer pass that forms a lower layer of the intersection portion and an upper layer pass that forms an upper layer of the intersection portion; and a welding condition decision section that decides welding conditions of the cross region passes in such a manner that an upper layer deposition amount per unit length of the deposition weld formed by the upper layer pass is larger than a lower layer deposition amount per unit length of the deposition weld formed by the lower layer pass, the sum of the upper layer deposition amount and the lower layer deposition amount is equal to a deposition amount per unit length of the deposition weld formed by the normal region pass, and the profiles of the deposition welds adjacent to each other in a cross section of the deposition weld formed by the upper layer pass orthogonal to the length direction overlap each other, the welding condition decision section changes the deposition amount by making the welding speed of the upper layer pass in the cross region pass slower than the welding speed of the lower layer pass, the lower layer deposition amount not being zero.

8. A recording medium storing a program that causes a computer to execute a layering process of a layering object, the layering process using a layering object production device that produces a deposition weld by melting and solidifying a filler material in layers, the layering object production device using shape data representing a three-dimensional shape of the layering object to produce the layering object, wherein the program causes the computer to implement the following functions: acquire the shape data; deciding a plurality of welding passes which form each layer obtained by layer-decomposing a three-dimensional shape of the layered molding based on the shape data through the deposition beads; classifying a plurality of the welding passes within the same layer of the layers into intersection region passes corresponding to intersection portions formed by a portion of a plurality of the deposition beads formed adjacently intersecting other plurality of the deposition beads and normal region passes corresponding to normal portions other than the intersection portions; deciding welding conditions of the intersection region passes each into a lower layer pass forming a lower layer of the intersection portions and an upper layer pass forming an upper layer of the intersection portions; and deciding the welding conditions of the intersection region passes in such a manner that an upper layer deposition amount per unit length of a deposition bead formed by the upper layer pass is larger than a lower layer deposition amount per unit length of a deposition bead formed by the lower layer pass, a sum of the upper layer deposition amount and the lower layer deposition amount is equal to a deposition amount per unit length of a deposition bead formed by the normal region passes, and outlines of the deposition beads formed by the upper layer pass overlap each other in a cross section of the deposition bead formed by the upper layer pass orthogonal to a length direction, the deposition amounts are changed by making a welding speed of the upper layer pass in the intersection region passes slower than a welding speed of the lower layer pass, the lower layer deposition amount being not zero.

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